Camera controls for coupled and non-coupled objectives

ABSTRACT

Controls for cameras adpated to use coupled and non-coupled objectives interchangeably. An electrical circuit is provided for utilizing a variable resistor with a coupled objective and direct light measurement through a stopped-down diaphragm with a noncoupled objective, these different operations being determined by a manually operable switch. In the event that a non-coupled objective is mounted on the camera and this latter manually operable switch is not positioned to directly measure light through the stopped-down diaphragm, the exposure time is the equivalent of a bulb exposure, lasting only until the operator releases a shutter-tripping member.

United States Patent [191 Suzuki [111 3,747,485 July 24, 1973 CAMERACONTROLS FOR COUPLED AND NON-COUPLED OBJECTIVES Inventor:

Minor-u Suzuki, Tokyo, Japan Asalii Kogaku Kogyo Kabushiki Kaisha,Tokyo-to, Japan Filed: Aug. 16, 1972 Appl. No.2 281,024

Assignee:

Foreign Application Priority Data Sept. 9, 1971 Japan 46/69874 US. Cl.95/10 CT, 95/42, 95/53 EB, 95/64 B Int, Cl G031) 7/08, G03b 7/20, G03b13/22 Field of Search. 95/10CT, 64 B, 42,

References Cited UNITED STATES PATENTS 3,683,765 8/1972 Yukiio lura95/42 X 3,678,823 7 7/1972 Takayoshi Sato 95/42 X 8c 8d Shutter Closing20a.

3,650,193 3/1972 Munetaka Shimizu 95/10 CT X 3,703,136 11/1972 Schwarz95/42 3,563,153 2/1971 Koichiro Watanabe 95/64 B Primary Examiner-JosephF. Peters, Jr. Attorney-Harold D. Steinbert et al.

[57] ABSTRACT Controls for cameras adpated to use coupled and noncoupledobjectives interchangeably. An electrical circuit is provided forutilizing a variable resistor with a coupled objective and direct lightmeasurement 7 through a stopped-down diaphragm with a non-coupledobjective, these different operations being determined by a manuallyoperable switch. In the event that a noncoupled objective is mounted onthe camera and this latter manually operable switch is not positioned todirectly measure light through the stopped-down diaphragm, the exposuretime is the equivalent of a bulb exposure, lasting only until theoperator releases a shutter-tripping member.

7 Claims, 7 Drawing Figures Dig ah rag m PArzmtuJmwm I v v 3.147. 485SHEET 2 (IF 2 CAMERA CONTROLS FOR COUPLED AND NON-COUPLED OBJECTIVESBACKGROUND OF THE INVENTION exposure time automatically. When a coupledtype of v objective is used with the camera, this objectiveautomatically sets a variable resistor of the circuit to provide aresistance value corresponding to the selected size of the exposureaperture. However, when a noncoupled objective is used with such acamera, the variable resistor is not automatically set. With this lattertype of objective it is necessary first to stop the objective down tothe selected aperture and then to trip the shutter so that the exposureis automatically made with direct measurement of light which passesthrough the stop-down diaphragm. The electrical circuit of the cameraincludes a switch set by the operator either in a fully-open diaphragmposition for operating with a coupled objective or in a stopped-downdiaphragm position for operating with a non-coupled objective. in theevent that a non-coupled objective is used while this latter switch isset in the fully-open diaphragm position, because the operator hasneglected to displace it to the stopped-down diaphragm position, animproper exposure is, made, and. with conventionaljcameras a timeexposure is made under these conditions.

Thus, it is conventional to operate cameras of the abovetype both withcoupled and non-coupledobjectives. Thenon-coupled objectives areincapable of automatically placing the electrical circuitry in aposition whichwill take into account-the selected exposure aperture'.For example cameras Offtllfl above type may have attached thereto anobjective utilizing an accessory such as aclose-range photography ring,and with such an arrangement there is no .automatic setting of thevariable resistor referred to above in accordance with the preselecteddiaphragm setting. it is therefore essential when using'a non-coupledobjective to place the circuit in a conditionwhere it will be capable ofoperating with light measured through the stop-down diaphragm. Thus,with cameras of this type a proper exposure will not be obtained with anon-coupled objective unless the latter happens to be set at theposition for the largest aperture. i

With a single lens reflex camera which measures light which has alreadypassed through the camera objective, the object brightness before thediaphragm is stopped down tothe selected aperture and before the mirrorswings up is sensedby a light-receiving element situated in. the camerabehind the objective. The resulting electrical signal is temporarilymemorized. When an exposure is to be made the diaphragm is automaticallystopped down to the preselected setting and the mirror swings up,whereupon the shutter is actuated and a proper exposure is made by wayof the exposuretime determining circuit on the basis of the memorizedsignal, as well as on the basis of the signals introduced in accordancewith the selected aperture of the diaphragm and the speed of the filmwhich is used in the cameral However, a non-coupled type of objectivecannot introduce into the electrical circuitry the factor of thepreselected aperture setting. In this case it is necessary to set thecircuit so as to be capable of operating with light measured through thediaphragm after the latter has been stopped down. For example, thepreselected aperture setting may be F5 .6, while the fully opendiaphragm setting may be F2. It is conventional for the operator to lookthrough the viewfinder at the object to be photographed while thediaphragm is set at its largest aperture, and if light measurement ismade while the aperture remains at its largest setting and then thediaphragm is automatically stopped down to the preselected setting, itis clear that there will be an underexposure, in this case a three-stageunderexposure resulting from light measurement with a setting of F2 andstopping down of the objective to F5.6 during the actual exposure. Ifindeed the diaphragm is set at the largest aperture F2 and this is theaperture selected for exposure, then in this case itwill be possible tomake a proper exposure even with a non-coupled type of objective. Thus,in those cases where the operator neglects to stop the diaphragm down tothe preselected setting before actuating a shutter-tripping plunger witha non-coupled objective which will be stopped down to the preselectedaperture aftershutter-tripping operations have been initiated, it isclear that light measurement is made with a setting of the diaphragmwhich is larger than the actual setting during actual exposure,resulting in underexposures.

It is possible to properly use non-coupled objectives with cameras ofthe above type if the camera is initially set so as to operate with suchan objective. Thus, when a coupled type of objective is removed from thecamera and replaced by a non-coupled objective of any type, it isnecessary to provide a functional change-over in the circuitry fromfully-open diaphragm light measurement to non-connection lightmeasurement where the signal is achieved by measurement of light throughthe stop-down diaphragm. Under these conditions the op erator may closethe, circuitry to start the lightmeasurement operation, and there willappear an indication warning of the non-connection of the variableresistor which is operated by a coupled-type of objective. if theoperator should continue under these conditions to trip the shutter, thenon-connection circuitry acts in such a way as to make a time exposure,thereby warning the user that an improper exposure has been made. Ofcourse, it is possible for the operator to change the circuitry over tooperate properly with'the stop-down diaphragm light measurement by meansof a manually operable stop-down diaphragm changeover member so as tocarry out exposure with the stopdown diaphragm in a proper manner.

With cameras having electrical circuitry of the above type, anarrangement is made to spare the operator the trouble of maintaining theshutter-tripping plunger depressed for a long period of time as, forexample, when an exposure is made under low-light conditions such asexposures made during the night. In this case an automatic structureoperates to maintain the current-source main switch closed until aproper exposure time has elapsed. Thus, with this type of constructiononce the shutter-release button is depressed, the main switch forcoupled type of diaphragm where proper precautions have not been takento expose the film with light measured through the stop-down diaphragm,then there is a disadvantage with conventional cameras in that as aresult a time exposure is made, resulting in undesirable waste ofbattery power.

SUMMARY OF THE INVENTION It is accordingly a primary object of thepresent invention to provide a camera of the above general type whichwill avoid the above drawbacks.

Thus, it is a primary object of the present invention to provide acamera capable of interchangeably using objectives of different typesand at the same time capable of minimizing possible lossesresulting fromthe fact that the operator neglects to set the camera to operate in amanner which is consistent with the type of objective' which is mountedon the camera.

In particular, it is an object of the invention to provide a cameracapable of eliminating the drawbacks inherent in conventional cameraswhich automatically provide time exposures in the event that the camerais set to operate with a coupled objective of the fullyopen diaphragmtype and in fact has mounted thereon a non-coupled objective which isincapable of automatically setting a variable resistorof an electriccircuit to compensate for the light measurement with a fully opendiaphragm. r

A more specific object of the invention is to provide a constructionaccording to which the duration of exposure will equal that of a bulbexposure in the event that the camera is set to operate with a coupledobjective when in fact a non-coupled objective-is mounted thereon.

A further object of the invention is to provide a camera which willavoid erroneous operation of the automatic structureof the camera in asituation which is the reverse of that referred to above in that a fullyopen type of coupled objective is mounted on the camera and the camerais set tooperate with a non-coupled type of automatic objective.

In addition, it is an object of the invention to provide structurecapable of achieving the above results in a simple highlyeffectivemanner which will not undesirably increase the cost of the camera andwhich also will not undesirably increase the size of the camera or thenumber of components which must be incorporated into the camera.

In accordance with the invention the single lens reflex camera isadapted to use interchangeable objectives both of the coupled and of thenon-coupled type. The camera has a photosensitive meansfor measuringlight after the light has travelled through a selected objective whichis mounted on the camera. A manually operable shutter-tripping meansismovable by the operator from a starting positionto a shutter-trippingposition and automatically returns to its starting position whenreleased by the operator. An electrical circuit means is electricallyconnected with the photosensitive means for automatically determiningthe exposure time, this electrical circuit means includes a main switchmeans having with respect to the shuttertripping means a position whichcloses the main switch means and thus the electrical circuit means forenergizing the latter upon movement of the shutter-tripping means awayfrom its starting position toward its shut ter-tripping position. Areleasable retaining means coacts with the main switch means forretaining the latter in its closed position after the shutter-trippingmeans is released for return to its starting position until the shuttercloses, this releasable retaining means responding automatically toclosing of the shutter for releasing the main switch means for return toits open position. The electrical circuit means further includes avariable resistor means, which coacts with a coupled objective tointroduce into the electrical circuit means a resistance value inaccordance with a preselected diaphragm setting when a coupled objectiveis mounted on the camera. A manually operable switch means forms part ofthe electrical circuit means and has a fully-open diaphragm positionconnecting the variable resistor means into the electrical circuit meansin series with the pho tosensitive means and a stop-down diaphragmposition connecting the photosensitive means into the electrical circuitmeans while disconnecting the variable resistor means fromthe electricalcircuit means, and a control means is provided for automatically openingthe main switch means to terminate operation of the electrical circuitmeans upon release of the shutter-tripping means for return to itsstarting position in the event that the manually operable switch meanshas not been dis placed to its stopped-down diaphragm position when anon-coupled objective is mounted on the camera, so

that in this latter event the equivalent of a bulb exposure is made.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way ofexample in the accompanying drawings which form part of this application and in which:

FIG. 1 is a schematic block and wiring diagram of circuitry of theinvention;

FIG. 2 is a schematic partly exploded perspective illustration ofdetails of one embodiment of the invention;

FIG. 3 shows in a perspective view part of the structure of FIG. 2 in aposition where a releasable retaining means retains a main switch meansin its closed position;

FIG. 4 is a perspective illustration of the structure of FIG. 3 afterclosing of the shutter brings about release of the main switch means forreturn to its open position;

FIG. 5 shows part of the structure of FIG. 2 in the position it takeswhen a releasable retaining means is retracted to a retracted positionhaving no effect on the main switch means;

FIG. 6 is a schematic illustration of another embodiment of a structureaccording to the invention; and

FIG. 7 is a fragmentary illustration of an electromagnet which mayreplace a switching circuit of FIG. 6 in accordance with a thirdembodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, the circuitryillustrated therein is for the most part conventional. Thus, FIG. 1shows a source of current 1 connected to the illustrated electricalcircuit means which includes a photosensitive means 2 in the form of alight-receiving component situated in the camera behind the objective torespond to light after the light has travelled through the objective inorder to measure the intensity'of the light and provide a correspondingelectrical. quantity. The electrical circuit means of FIG. 1 includes anindicating meter 3 connected in parallel with a capacitor 5 when theswitches S3 and S4 have the solid line positionindi- 7 means of FIG. 1includes an electromagnet means 7 which when energized retains theshutter in its open position and when deenergized releases the trailingcurmm of the shutter to close the shutter in a well known manner. A mainswitch means is formed by the current source switch S1, and the circuitmeans also includes the timing switch S2 which when closed bypasses thetiming capacitor 6 and which when opened renders the timing capacitor 6operative. The switches S3 and S4 operate together to change over fromthe solid line position of FIG. 1 where the memory capacitor 5 ischarged to the dotted line position of FIG. 1 where the charge memorizedby and stored in the capacitor 5 is used for influencing the timingportion of the electrical circuit means in order to determine in a wellknown manner the exposure time. These change-over switches S3 and S4 arearranged so as to be operated after closure of the main switch means S1in driving connection with, for example, the initial part of thedepression movement of the shutter-tripping means, so that just beforethe shutter is released to open and make an exposure the memorycapacitor 5 is separated from the measurement circuit A and connectedwith the control I circuit B. A change-over switch S5 forms part ofamanually operable switch means of the invention for changing over fromthe illustrated fully-open diaphragm position to a stopped-downdiaphragm position where the switch S5 no longer connects the variableresistor 4 in series with the photosensitive means 2 and insteadconnects the photosensitive means 2 directly into the circuit whiledisconnecting the variable resistor means therefrom. Thus, when theswitch S5 is in the position shown in FIG. 1, the variable resistormeans 4 is operative and a fully-open diaphragm light measurementoperation can be carried out with a coupled objective.

The electrical circuit means further includes a switch S6 connected inseries with the variable resistor means 4 and arranged so as to beopened when a fully-open diaphragm type of coupled objectiveis removedfrom the camera, so that in this way the operator can receive a warningthat the exposure meter 3 is not connected into the circuit. a

Referring to FIG. 2, it will be seen that the camera includes ashutter-tripping means formed by an elongated rod 8 which is connectedto the shutter button and which is depressed by the operator so as tomove downwardly from the starting position illustrated in FIG. 2 towarda tripping position where the shutter is tripped so as to assume itsopen position in a well known manner. The rod 8 of the shutter-trippingmeans fixedly carries a radially extending pin 8a which during downwardmovement of the rod 8 brings about automatic'closing of the main switchmeans S1. Thus, as

may be seen from FIG. 2, the pin 8a is located directly over an arm 20aof a bell crank 20 supported for swinging movement on a pivot pin 20c.The second arm 20b of the bell crank carries a pin 21 made of aninsulating 5 material and engaging the left leaf of the switch S1 shownat the left of FIG. 2. Therefore when the operator moves the rod 8downwardly the lever 20 swings in a clockwise direction to move the pin21 to the right and thus close the main switch means S1.

With this closing of the main switch means S1 the electrical circuitmeans of FIG. 1 is energized, and the photosensitive means 2 is'renderedoperative to respond to the intensity of the light which has travelledthrough the objective, this photosensitive means 2 together with themeasurement circuit A which is conventional providing an output voltagewhich is proportional to the APEX number of object brightness, thisvoltage being developed at one pole of the memory capacitor 5. At thesame time, a second output voltage which is an electrically transformedvalue corresponding to the APEX representation of exposure conditionsother than object brightness, namely F value and film speed, isdeveloped at the other pole or terminal of the memory capacitor 5. As aresult, the voltage across the memory capacitor 5 has a value determinedin accordance with the exposure conditions of object brightness,F-value, and film speed. Themeter 3 which is connected in parallel withthe memory capacitor 5 has an exposure time scale according to APEXvalues, so that the meter 3 which is visible to the operator provides anindication of the exposure time which will be produced under theparticular photographing conditions. In other words the meter 3 willindicate the exposure time which will be provided by the camera inaccordance with the intensity of thelight, the selected exposureaperture, and the film speed.

As was pointed out above, during the first or initial part of thedownward movement of the shutter-tripping means 8, the main switchmeansS1 is closed. During an intermediate part of the downward movement ofthe shutter-tripping means 8 toward its shutter-tripping position,before actual tripping of the shutter, the switches S3. and S4 arechanged over from their connection to the circuit A into theirconnection to the circuit B. Thus, FIG. 2 shows schematically how aspring 8e normally maintains the switches S3 and S4 in th solid lineposition of FIG. 1 while a lever 8d is acted upon by the pin 8b duringthe intermediate part of the downward movement of the rod 8 in order tochange the switches S3 and S4 over into their connection with thecontrol circuit B. In this way the memory capacitor 5 is inserted into aretaining circuit which retains the charge which corresponds to thevoltage across the capacitor 5. The control circuit B which has a highinput resistance retaining circuit controls the current which chargesthe timing capacitor 6 in accordance with the voltage across the memorycapacitor 5.

During the final part of the downward movement of the shutter-trippingmeans 8 from its starting position toward its shutter-tripping position,the pin 8b brings about in a known way swinging up of the mirror of thereflex camera, automatic stopping-down of the diaphragm, also in a wellmanner, and immediately thereafter opening of the shutter withsimultaneous opening place in a well known manner which does not formpart of the present invention.

of the timing switch S2, this latter operation also taking The timeduring which the capacitor 6 is charged upon opening of the switch S2determines the exposure time in accordance with the charging currentcontrolled by the control circuit B, and when the charge at the timingcapacitor 6 reaches a given value the voltage across the capacitor 6will reach a corresponding value automatically bringing about operationof the switching circuit C,'which may be a form of Schmitt circuit, soas to deenergize the electromagnet 7, thereby releasing the trailingcurtain of the shutter so that the shutter immediately closes and theexposure is terminated.

Upon closing of the shutter the switch S1 opens, the mirror swingsbackdown to its position for reflecting light from the objective to theviewfinder, and the diaphragm automatically returns to its fully openposition, all of these operations taking place in a well known manner,so that in this way a complete cycle of photographing operations iscompleted.

Upon removal of a fully-open diaphragm type of coupled objective fromthe camera, the switch S6 automatically opens, in the manner describedin greater detail below, so that one of the poles or terminals of thememory capacitor is not charged in accordance with an output voltagerepresenting as an electrical quantity exposure factors other thanobject brightness, such as the factor of the selected diaphragm apertureand the film speed, and at this time the indicating meter 3 indicates anon-connection, thus letting the operator know that the camera must beoperated in the manner required when a non-coupled objective is mountedthereon. Under these conditions the switching circuit C does not operateso that current will continue to flow through the winding of theelectromagnet means 7. Therefore under these conditions shutter closingaction is not automatically initiated after a lapse of timecorresponding to a proper exposure time, and instead the shutter isoperated according to a time exposure.

Measurement of the light is carried out with a stopped-down diaphragm bychanging over the switch means S5 to the'stopped-down diaphragmside'where the switch S5 no longer connects the variable resistor 4 intothe circuit and serves at this time to connect the photosensitive means2 directly into the circuit. Under these conditions the charge stored atthe memory capacitor 5 is determined by way of the setting of thediaphragm by the diaphragm ring of the objective, and

shutter control operation is then carried out in the same way asdescribed above.

FIG. 2 schematically illustrates a fully-open diaphragm type of coupledobjective 9 capable of being mounted on the camera. This objective 9 hasan aperture selecting ring 10 which in the position illustrated in FIG.2 has been turned so as to select an aperture of F8. Theaperture-selecting ring 10 has a coupling projection 11. through whichhis capable of operating a first transmission means 13 in order to bringabout automatic setting of the variable resistor means 4. This firsttransmission means 13 includes the illustrated ring 13 having a couplingprojection 12 engaged by the coupling projection 11 so that rotarymovement of the ring 10 is transmitted to the ring 13 for turning thelatter around the optical axis, this ring 13 of the firstmotiontransmitting means being supported for rotary movement abouttheoptical axis in any suitable way. The elongated projection 12normally engages the projection I! at the front end of the projection 12while the rear end thereof carries a brush 4a of the variable resistormeans 4. This variable resistor means has at its left end, as viewed inFIG. 2, an insulating or electrically non-conductive portion 4b. Thearrangement is such that when the brush 4a engages the insulatingportion 4b, the switch S6 of FIG. 1 is opened so as to establish anon-connection light measurement circuit. Thus, referring to FIG. 5,there is schematically illustrated therein the switch S6 which isnormally urged by a spring to its closed position, this switch having apart located in the path of movement of the projection 12 so that whenthe ring 13 turns to the position shown in FIG. 5 the switch S6 assumesthe open position shown in FIG. 5. l

The first transmission means formed by the ring 13 is urged to a restposition in a counterclockwise direction from the position of FIG. 2into the rest position illustrated in FIG. 5 by a spring means 16connected to a wire 15 which extends around and is fixed to the ring 13.Therefore when the projection 12 is not acted upon by the projection 11of a coupled type of objective 9, the spring means 16 will return thefirst transmission means 13 to the rest position which is shown in FIG.5.

This first transmission means includes a lug 13a of the ring 13, andthis lug 13a engages a swingable lever 14 of a second transmission meansfor swinging the lever 14 from the position of FIG. 2 into the positionof FIG. 5 when the first transmission means returns to the rest positionshown in FIG. 5. Thus, it will be seen that tle swingable lever 14 of thsecond transmission means is supported for swinging movement on astationary pivot pin 14a and has its clockwise rotary movement limitedby a stationary stop member 30.

The second transmission means includes an elongated wire 29 connected atone end to a pin 14b which is fixed to the swing lever 14.

The manually operable switch means S5 includes a lever 17 fixed to a pinwhich is supported for rotary movement about a horizontal axis parallelto the optical axis, this lever 17 being accessible to the operator. Thelever 17 is fixed to a second lever 18 which extends perpendicularlywith respect to the lever 17 and which carries a roller 19 which isparallel to the turning axis of the levers 17, 18. The lever meansformed by the assembly 17, 18 is operatively connected with th switch S5in the manner shown schematically in FIG. 1, so that when the lever 17is in the solid fully-open diaphragm position shown in FIG. 2 the switchS5 is connected with the variable resistor means 4, while when the lever17 is'turned by the operator in a clockwise direction, as viewed inFIGS. 1,2, and 5, to the phantom-line position, the manually operableswitch means is placed in its stopped-down diaphragm position where theswitch S5 is no longer connected with the variable resistor means 4 butinstead connects the photosensitive means 2 directly into the circuitwhile disconnecting the vari able resistor means 4 therefrom, asdescribed above. Thus, swinging of the lever 17 by the operator to thestopped-down diaphragm position shown in phantom lines brings aboutchanging over of the switch S5 to the position for measuring light whichtravels through the stopped-down diaphragm, and in addition automaticdiaphragm stopping down operations will be carried out in a well knownmanner. Suitable detent structure may be provided for providingclick-setoperation of the manually operable switch means releasably retaining thelever 17 in either of its positions, namely the fully-open diaphragmposition and the stopped-down diaphragm position indicated in FIG. 2.The roller 19 carried by the arm 18 engages the wire 29 of the secondtransmission means for controlling a releasable retaining means referredto below in a manner described in greater detail.

Thus, the wire 29 is connected at one end to the pin 14b of the swinglever 14 of the second transmission means, as referred to above. Thewire 29 is guided around the rollers 27 and 28, with the roller 19engaging the wire between the rollers 27 and 28. The roller 27 iscarried by a swingable lever which is acted upon by a spring so that inthis way any slack in the wire 29 will be automatically taken up.

The releasable retaining means which serves in a manner described belowto releasably retain the main switch means 81 in its open position afterthe operator releases the shutter-tripping means 8 for return to itsstarting position includes a swingable lever 25 supported for swingingmovement on a pivot 25a and carrying a pin 26 to which is connected theend of the wire 29 distant from the pin 14b. The pin 26 which is carriedby the lever 25 and to which the wire 29 is fixed in this way alsoserves as a pivot for supporting a lever 23 of the releasable retainingmeans for swinging movement about a vertical axis parallel to the axisabout which the lever 25 turns, this axis being perpendicular to theoptical axis. A spring 24 is connected at one end to the arm 23a of thelever 23 and at its opposite end to a pin carried by the lever 25 so asto urge the retaining lever 23 I to swing in a counterclockwisedirection as viewed in FIG. 2. A spring 32 is operatively connected withthe lever 25 for urging the lever 25 to turn also in a counterclockwisedirection, as viewed in the drawings, into engagement with a stop member3]. Thus, the spring 32 normally urges the lever 25 into engagement withthe stop member 31.

In the position of the part shown in FIG. 2 where the shutter-trippingmeans 8 is in its starting position, the

I free end of the arm 20a of the'bell crank which forms the lever 20 issituated in front of the free end of the close the main switch means S1,and during an intermediate part of the movement of the shutter-trippingmeans' 8, the pin 81) brings about a change-over of the switches S3 andS4 to connect the capacitor 5 to the control circuit B, and also at thispart of the operation the mirror is swung up and the diaphragm isstopped down to the preselected aperture just prior to actual opening ofthe shutter to initiate the exposure.

The releasable retaining means formed by the components 23-26 respondsautomatically to closing of the shutter for releasing the switch meansS1 to assume again its normally open position. For this purpose thereis-a rotary disc 33 operatively connected with the trailing curtain ofthe shutter in such a way that the disc 33 -turns in a counterclockwisedirection, as indicated by the arrow in FIG. 2, when the shutter closes.This disc 33 carries a pin 34 which engages the arm 23b of the bellcrank 23 for turning the latter in a clockwise direction in oppositionto the spring 24 so that the lever 23 will again assume the positionshown in FIG. 2 and the lever 20 will also again assume the positionshown in FIG. 2 in response to closing of the shutter.

FIG. 2 further illustrates a return spring 22 acting on theshutter-tripping means 8 for urging back to its starting position. Also,FIG. 2 shows schematically how the photosensitive means 2 is situated inthe interior of the camera behind the objective to receive light afterthe light has travelled through the objective.

FIG. 3 illustrates how the arm 23a of the releasable retaining meansbecomes located over the arm 20a of the main switch means in order tomaintain the main switch means in its closed position shown in FIG. 3even after the shutter-tripping means 8 returns to its startingposition. Thus, as soon as the pin swings the lever 20 into the positionshown in FIG. 3 in order to close the main switch means 81, the lever 23is turned by the spring 24 to locate the arm 23a over the arm 20a andthus prevent the switch means 81 from opening.

FIG. 4 illustrates how upon closing of the shutter the disc 33 turns todisplace the lever 23 in a clockwisedirection through the pin 34, thusreleasing the switch means S1 to assume again its open position, and ofcourse when the disc 33 returns to the position shown in FIG. 2 the arm23a will be turned by the spring 24 into engagement with the arm 20awhich prevents further turning of the lever 23, the parts now having theposition shown in FIG. 2.

FIG. 5 illustrates how the first and second transmission means operateto retract the releasable retaining means 23-26 to a retracted positionwhere it has no influence on the operation of the main switch means S1.Thus, when the first transmission means 13 is returned to its restposition by the spring means 16, the lug 13a swings the lever 14 of thesecond transmission means away from the stop 30, and this movement istransmitted through the wire 29 to the pin 26 carried by the lever 25,so that the lever 25 is in turn swung around the pivot 25a away from thestop 31 in'opposition to the spring 32, and thus the entire releasableretaining means is retracted to the position shown in FIG. 5 where thelever 23 is situated beyond the lever 20 and thus can have no influenceon the operation of the main switch means. Under these conditions assoon as the operator releases the shutter-tripping means 8 for return toits starting position, the main switch means 81 will open and theelectromagnet 7 will become unenergized so as to automatically terminatethe exposure.

Assuming that a fully-open diaphragm type of coupled objective 9 ismounted on the camera and that the manually operable switch means hasits lever 17 in the proper fully-open diaphragm position shown in solidlines in FIGS. 2 and 5, then the coupling projection 11 of thediaphragm-selecting ring 10 engages the coupling projection 12 of thefirst transmission means 13 in order to turn the latter for situatingthe brush 4a of the variable resistor means 4 at a position where thisvariable resistor means 4 will introduce into the circuit an electricalquantity corresponding to the selected diaphragm setting. Thus, becauseof the compensation provided by way of the variable resistor means 4 itis possible to carry out light measurement at the photosensitive means 2through the fully open diaphragm. Of course, situation of the lever 17in the fully-open diaphragm position places the manually operable switchmeans S in its position connecting the'variable resistor.

means 4 into the circuit, as shown in FIG. 1, and at the same time theswitch S6 is automatically closed because the rear part of theprojection 12 no longer engages the normally closed switch S6.

Under these conditions during the initial part of the downward movementof the shutter-tripping means 8, the pin 8a thereof swings the lever ofthe main switch means so as to close the main switch means S1. A fullyopen diaphragm light measurement is now carried out and the memorycharge stored by the memory capacitor 5 is determined in this way.Further depression of the shutter-tripping means 8 through the middlepart of its downward movement causes the pin 8b to act so as to switchpair of switches S3 and S4 over to the position placing the capacitor 5in connection with the control circuit B, and during this part of theoperation the mirror is swung up and the diaphragm is automaticallystopped down to the preselected setting. At the final part of thedownward movement of the rod 8 the shutter-tripping position is reachedso that the shutter opens. Although the operator releases theshuttertripping means 8 for return to its starting position, thereleasable retaining means acts at this time, in the manner shown inFIG. 3, to retain the switch means S1 closed. Thus, the releasableretaining means 23-26 remains at this time in its operating positionwhere it provides the operation shown in FIG. 3. Thus, the switch S1 isautomatically maintained in its closed position when the shutter opensand while the shutter remains open. After the automatically determinedexposure time has elapsed, the shutter closes since the electromagnetmeans 7 becomes unenergized, and at this time the disc 33 turns to bringabout swinging of the retaining lever 23 to the position of FIG. 4 inthe manner described above. As a result the main switch means S1 isreleased for return to its normal open position, and thus the electricalcircuit means of FIG. 1 no longer operates. Therefore, when a fully-opendiaphragm type of coupled objective 9 is mounted on the camera, and themanually operable switch means has its lever 17 set in the fully-opendiaphragm position, the main switch means S1 will remain closed duringthe entire time that the shutter remains open, independently of thereturn of the shutter-tripping means 8 to its starting position. Ofcourse, if the operator should maintain the shuttertripping means 8depressed in its shutter-tripping position after the shutter closes,then the switch S1 will open only upon release of the shutter-trippingmeans 8 by the operator for return to its starting position.

It is of course possible through an oversight that the manually operableswitch means will have its lever 17 located in the stopped-downdiaphragm position shown in phantom lines in FIG. 2 when a fully-opendiaphragm type of coupled objective 9 is attached to the camera. In thisevent the manually operable switch means S5 no longer connects thevariable resistor means 4 into the circuit. Instead this manuallyoperable switch means is in the position it takes for providing astopped-down diaphragm light measurement circuit, and, as is well known,operation with a stopped-down diaphragm can be carried out by way of thediaphragm ringIO. Because the arm 18 has been swung with the lever 17 tothe phantom line position shown in FIG. 2, the roller 19 at this timeacts on the wire 29 of the second transmission means to slacken the wire29 enabling the spring 32 to turn the lever into engagement with thestop 31 if it happens to be located close to the stop 31 but not inengagement therewith. The roller 27 acts to take up the slack, as waspointed out above. Thus, the releasable retaining means 23- 26 willstill remain in its operating position shown in FIG. 2 even under theseconditions, so that the main switch means S1 is operated in the same wayas described above. Thus, under these conditions charging of thecapacitor 5 will not be influenced by the variable resistor means 4.

Assuming that the fully-open diaphragm type of coupled objective 9 isremoved from the camera and replaced by a non-coupled objective and thatthe operator erroneously leaves the lever 17 in the fully-open diaphragmposition shown in solid lines in FIGS. 2 and 5, then the structure willoperate in the following manner:

The ring 13 will be returned by the spring 16 to the rest position shownin FIG. 5 so that the lug 13a of the first transmission means formed bythe ring 13 will swing the lever 14 of the second transmission means tothe position of FIG. 5, thus pulling on the wire 29 of the secondtransmission means in order to retract the releasable retaining means23-26 into its retracted posi' tion shown in FIG. 5 where it will haveno further influence on the main switch means S1. Under these conditionsthe main switch means S1 will be first closed and then opened upondepressionand release of the shutter-tripping means 8, respectively.Therefore, when the operator erroneously depresses the shutter buttonwith the non-coupled type of objective attached to the camera and withthe manually operable switch means in the fully-open diaphragm position,the equivalent of a bulb exposure is made rather than a time exposure.In other words the duration of the exposure is determined by the timeduring which the operator maintains the shutter-tripping means 8depressed. As soon as the operator releases the shutter-tripping means 8the switch means S1 will automatically open under these conditions so asto terminate the exposure.

If, however, a non-coupled type of objective replaces the objective 9and the operator has correctly displaced the manually operable switchmeans so that its lever 17 is in the stopped-down diaphragm positionshown in phantom lines in the drawings, then the operations is asfollows:

The roller 19 of the manually operable switch means will act on the wire29 of the second transmission means to slacken the wire so that thespring 32 can still maintain the lever 25 in engagement with the stop31, thus maintaining the releasable retaining means in its operatingposition even though the lever 14 has been turned to the position ofFIG. 5 by the first transmission means 13. Thus, the releasableretaining means will be fully operative under these conditions, in thesame manner as described above in connection with the fu|- ly-opendiaphragm type of objective 9, and the depression of theshutter-tripping means 8 will bring about closing of the switch means S1with the opening thereof being determined by closing of the shutterrather than by release of the shutter-tripping means 8. Of course, underthese conditions the non-coupled objective may be automatically stoppeddown either manually before the shutter-tripping means 8 is depressed inorder to initiate an exposure, so that light measurement by thephotosensitive means 2 is made only through the stopped-down objective,or the non-coupled type of objective may be one which is automaticallystopped down prior to closing of the main switch means S1 in order toenergize the photosensitive means 2, so that in either case the lightmeasurement will be made only through the stopped-down diaphragm, thusachieving a proper exposure with the variable resistor means 4disconnected from the circuit.

With conventional cameras the arrangement is such that when the lightmeasurement change-over means remains set in the position-for fully-opendiaphragm light measurement and the user erroneously depresses theshutter button with a non-coupled type of objective connected to thecamera, a warning is given by way of the action of the non-connectioncircuit and the shutter will carry out a time exposure. In accordancewith the present invention, however, a considerable advantage isachieved in that under these circumstances the releasable retainingmeans is rendered inactive and the opening and closing of the mainswitch means is carried out directly in response to operation of theshuttertripping means. Therefore inadvertent depression of theshutter-tripping means under these conditions will only result in a bulbexposure, so that the excessive powerconsumption resulting from a timeexposure is avoided and in addition the bulb exposure action of theshutter will warn the operator immediately that there has been anerroneous operation, so that the operator is warned earlier with thepresent invention than with conventional systems.

With electrical shutter-control systems of the type shown in FIG. 1,power is consumed'primarily at the shutter-controlling electromagnetmeans 7. Therefore, in addition to the above-described embodiment of theinvention, it is possible to provide other arrangements which willachieve the advantages of the invention. Thus, while with theabove-described embodiment of the invention, the releasable retainingmeans is retracted so asto have no effect on the main switch means S1,thus achieving opening of the latter when the operator releases theshutter-tripping means 8 for return to its starting position, it is alsopossible to have circuitry in addition to that described above forachieving substantially the same result. It is possible in accordancewith the invention to provide other embodiments where the'secondtransmission means formed by the wire 29 is eliminated so that thereleasable retaining means remains at all times in its operatingposition, and instead upon return of the shutter-tripping means 8 towardits starting position either the electromagnet means 7 or the switchingcircuit means C is shortcircuited in the event that the manuallyoperable switch means S5 has its lever 17 in the fully-open diaphragmposition when in fact a non-coupled diaphragm is attachedto the camera.I

Thus, referring to FIG. 6, it will be seen that according to thisembodiment of the invention, the releasable retaining means 23-26 mayremain at all times in its operating position, and instead theshutter-tripping means 8 is provided with an additional pin 8fprojecting radially therefrom. This pin 8fis adapted to swing theschematically illustrated lever 8g in a clockwise direction, as viewedin FIG. 6, for closing a switch S7 when the shutter-tripping means 8returns to its starting position illustrated in FIG. 6. The switch S7 isconnected in series with a switch S8 which is coupled with the switch S5so as to operate in unison therewith. Thus, the switch S8 is closed whenthe switch S5 is in the fullyopen diaphragm position, connecting thevariable resistor means 4 into thecircuit. When the switch S5 is movedto the stopped-down diaphragm position the switch S8 is opened. Thisswitch S8 is in turn connected in series with a switch S9 which issituated beside the switch S6. The switch S9 is a normally open switch,and this switch is closed by the rear portion of the projection 12 whena non-coupled objective is connected to the camera. Thus, as wasdescribed above the spring 16 will turn the ring 13 to the position ofFIG. 5 when a non-coupled objective is mounted on the camera, and withthe embodiment of FIG. 6 the projection 12 will close the switch S9while simultaneously opening the switch S6. The series-connectedswitches S7, S8, and S9 are all connected in series with the switchingcircuit means C, so that with the parts in the position of FIG. 6 theswitching circuit means C will be short-circuited, thus bringing aboutdeenergizing of the electromagnet means 7 upon return of theshutter-tripping means 8 to its starting position shown in FIG. 6. Ofcourse, if a fully-open diaphragm type of coupled objective 9 is mountedon the camera, the switch S9 will be in its normally open positionpreventing operation of the circuit shown in FIG. 6, while if with anon-coupled objective on the camera the manually operable switch meansis properly positioned in the phantom-line position shown in FIGS. 2 and5, the switch S8 will be opened, thus preventing operation of thecircuit of FIG. 6 also under this latter condition.

However, if a non-coupled objective is mounted on remains in itsoperating position to hold the main switch means closed in the mannershown in FIG. 3, will be acted upon by the closing of the shutter, bywayof the disc 33 and the pin 34 as described above in connection with FIG.4, in order to immediately release the main switch means to assume itsopen position upon closing of the short-circuiting switch S7. Thereforewtih this structure also it is possible to achieve the results of theinvention described above.

With the embodiment of FIG. 7 the circuitry is the same as that of FIG.6 except that the electromagnet means 7 is located in the position ofthe switching circuit means C, so that it is the coil of theelectromagnet means 7 which is short-circuited under the conditionsdescribed above in connection with FIG. 6. This action also will resultin release of the shutter to assume its closed position, thus bringingabout the operation shown in FIG. 4 on the releasable retaining means,so that the switch S1 will automatically assume its open position assoon as the shutter-tripping means 8 returns to its starting position.Therefore, with these embodiments also it is possible to provide theequivalent of a bulb exposure when the lever 17 of the manually operableswitch means S5 remains in the fully-open diaphragm position when anon-coupled diaphragm is mounted on the camera.

What is claimed is:

1. In a single lens reflex camera adapted to use interchangeableobjectives of the coupled and non-coupled type, and having aphotosensitive means for measuring light after the light has travelledthrough a selected objective which is mounted on the camera, manuallyoperable shutter-tripping means movable by the operator from a startingposition to a shutter-tripping position and automatically returning tosaid starting position when released by the operator, electrical circuitmeans electrically connected with said photosensitive means forautomatically determining the exposure time, said electrical circuitmeans including a main switch means having with respect to saidshutter-tripping means a position which closes said main switch meansand thus said electrical circuit means for energizing the latter uponmovement of said shutter-tripping means away from said starting positionthereof toward said shuttertripping position thereof, releasableretaining means coacting with said main-switch means for retaining thelatter in its closed position after said shutter-tripping means isreleased for return to its starting position until the shutter closes,said releasable-retaining means responding automatically to closing ofthe shutter for releasing said main switch means for return to its openposition, said electrical circuit means further including a variableresistor means for coacting with a coupled objective to introduce intosaid electrical circuit means a resistance value in accordance with apreselected diaphragm setting when a coupled objective is mounted on thecamera, manually operable switch means forming part of said electricalcircuit means and having a fullyopen diaphragm position connecting saidvariable resistor means into said electrical circuit means in serieswith said photosensitive means and a stopped-down diaphragm positionconnecting said photosensitive means into said electrical circuit meanswhile disconnecting said variable resistor means from said electricalcircuit means, and control means for automatically opening said mainswitch means to terminate operation of said electrical circuit meansupon release of said shutter-tripping means for return to its startingposition -in the event that said manually operable switch .means has notbeen displaced to its stopped-down diaphragm position when a non-coupledobjective is mounted on the camera, so that in the latter event theequivalent of a bulb exposure is made.

2. The combination of claim 1 and wherein said releasable retainingmeans is movable between an operating position coacting with said mainswitch means and a retracted position where said releasable retainingmeans has no effect on said main switch means, said control meanscoacting with said releasable retaining means for automaticallyretracting the latter to said retracted position thereof when anon-coupled objective is mounted on the camera and said manuallyoperable switch means is in said fully-open diaphragm position thereof,said manually operable switch means coacting with said control means formaintaining said releasable retaining means in said operating positionthereof when a non-coupled objective is mounted on the camera and saidmanually operable switch means is displaced to said stop-down diaphragmposition thereof.

3. The combination of claim 2 and wherein a first motion-transmittingmeans is operatively connected with said variable resistor means forautomatically setting the latter-at a position corresponding to theposition of an aperture selecting ring ofa coupled objective when thelatter is mounted on the camera, spring means operatively connected withsaid first motion transmitting means for returning the latter to apredetermined rest position when a non-coupled objective is mounted onthe camera, and second motiontransmitting means actuated by said firstmotiontransmitting means upon return of the latter to said rest positionthereof and operatively connected with said releasable retaining meansfor automatically retracting the latter to said retracted positionthereof in response to movement of said first motion-transmitting meansto said rest position thereof, said manually operable switch meanscoacting with said second transmission means for acting on the latter tomaintain said releas able retaining means in said operating positionthereof when said first motion-transmitting means returns to said restposition thereof and acts on said second motion-transmitting means.

4. The combination of claim 3 and wherein said releasable retainingmeans is swingably mounted for movement between said operating andretracted positions, said second motion-transmitting means including aswingable lever and a wire extending between said swingable lever andsaid releasable retaining means, said first motion-transmitting meansincluding a rotary ring having a lug which acts on said swingable leverto act through the latter on said wire for retracting said releasableretaining means to said retracted position thereof, said manuallyoperable switch means including a lever having an arm operativelyconnected with said wire for acting through the latter on saidreleasable .retaining means for maintaining the latter in said operatingposition thereof even when said swingable lever is acted upon by saidlug of said first motion-transmitting means.

5. The combination of claim 1 and wherein said electrical circuit meansincludes an electromagnet means for retaining a camera shutter in itsopen position while said electromagnet means is energized and forreleasing the camera shutter to close when said electromagnet means isunenergized, said electrical circuit means including as part thereof aswitching circuit means electrically connected with said electromagnetmeans for deenergizing the latter after an exposure time determined bysaid electrical circuit means has elapsed, said releasable-retainingmeans responding to closing of the shutter for releasing said mainswitch means for return to its open position, said switching circuitmeans and electromagnet means forming a pair of means at least one ofwhich is electrically connected with said control means, and saidcontrol means including a switch means which automatically closes inresponse to return of said shutter-tripping means toward saidstartingposition thereof for short-circuiting said one of said pair ofmeans to deenergize said electromagnet means and thus permit the shutterto close for opening said main switch means.

6. The combination of claim 5 and wherein said one of said pair of meansis said electromagnet means.

7. The combination of claim 5 and wherein said one

1. In a single lens reflex camera adapted to use interchangeableobjectives of the coupled and non-coupled type, and having aphotosensitive means for measuring light after the light has travelledthrough a selected objective which is mounted on the camera, manuallyoperable shutter-tripping means movable by the operator from a startingposition to a shutter-tripping position and automatically returning tosaid starting position when released by the operator, electrical circuitmeans electrically connected with said photosensitive means forautomatically determining the exposure time, said electrical circuitmeans including a main switch means having with respect to saidshutter-tripping means a position which closes said main switch meansand thus said electrical circuit means for energizing the latter uponmovement of said shutter-tripping means away from said starting positionthereof toward said shutter-tripping position thereof, releasableretaining means coacting with said main-switch means for retaining thelatter in its closed position after said shutter-tripping means isreleased for return to its starting position until the shutter closes,said releasableretaining means responding automatically to closing ofthe shutter for releasing said main switch means for return to its openposition, said electrical circuit means further including a variableresistor means for coacting with a coupled objective to introduce intosaid electrical circuit means a resistance value in accordance with apreselected diaphragm setting when a coupled objective is mounted on thecamera, manually operable switch means forming part of said electricalcircuit means and having a fully-open diaphragm position connecting saidvariable resistor means into said electrical circuit means in serieswith said photosensitive means and a stopped-down diaphragm positionconnecting said photosensitive means into said electrical circuit meanswhile disconnecting said variable resistor means from said electricalcircuit means, and control means for automatically opening said mainswitch means to terminate operation of said electrical circuit meansupon release of said shutter-tripping means for return to its startingposition in the event that said manually operable switch means has notbeen displaced to its stopped-down diaphragm position when a non-coupledobjective is mounted on the camera, so that in the latter event theequivalent of a bulb exposure is made.
 2. The combination of claim 1 andwherein said releasable retaining means is movable between an operatingposition coacting with said main switch means and a retracted positionwhere said releasable retaining means has no effect on said main switchmeans, said control means coacting with said releasable retaining meansfor automatically retracting the latter to said retracted positionthereof when a non-coupled objective is mounted on the camera and saidmanually operable switch means is in said fully-open diaphragm positionthereof, said manually operable switch means coacting with said controlmeans for maintaining said releasable retaining means in said operatingposition thereof when a non-coupled objective is mounted on the cameraand said manually operable switch means is displaced to said stop-downdiaphragm position thereof.
 3. The combination of claim 2 and wherein afirst motion-transmitting means is operatively connected with saidvariable resistor means for automatically setting the latter at aposition corresponding to the position of an aperture selecting ring ofa coupled objective when the latter is mounted on the camera, springmeans operatively connected with said first motion-transmitting meansfor returning the latter to a predetermined rest position when anon-coupled objective is mounted on the camera, and secondmotion-transmitting means actuated by said first motion-transmittingmeans upon return of the latter to said rest position thereof andoperatively connected with said releasable retaining means forautomatically retracting the latter to said retracted position thereofin response to movement of said first motion-transmitting means to saidrest position thereof, said manually operable switch means coacting withsaid second transmission means for acting on the latter to maintain saidreleasable retaining means in said operating position thereof when saidfirst motion-transmitting means returns to said rest position thereofand acts on said second motion-transmitting means.
 4. The combination ofclaim 3 and wherein said releasable retaining means is swingably mountedfor movement between said operating and retracted positions, said secondmotion-transmitting means including a swingable lever and a wireextending between said swingable lever and said releasable retainingmeans, said first motion-transmitting means including a rotary ringhaving a lug which acts on said swingable lever to act through thelatter on said wire for retracting said releasable retaining means tosaid retracted position thereof, said manually operable switch meansincluding a lever having an arm operatively connected with said wire foracting through the latter on said releasable retaining means formaintaining the latter in said operating position thereof even when saidswingable lever is acted upon by said lug of said firstmotion-transmitting means.
 5. The combination of claim 1 and whereinsaid electrical circuit means includes an electromagnet means forretaining a camera shutter in its open position while said electromagnetmeans is energized and for releasing the camera shutter to close whensaid electromagnet means is unenergized, said electrical circuit meansincluding as part thereof a switching circuit means electricallyconnected with said electromagnet means for deenergizing the latterafter an exposure time determined by said electrical circuit means haselapsed, said releasable-retaining means responding to closing of theshutter for releasing said main switch means for return to its openposition, said switching circuit means and electromagnet means forming apair of means at least one of which is electrically connected with saidcontrol means, and said control means including a switch means whichautomatically closes in response to return of said shutter-trippingmeans toward said starting position thereof for short-circuiting saidone of said pair of means to deenergize said electromagnet means andthus permit the shutter to close for opening said main switch means. 6.The combination of claim 5 and wherein said one of said pair of means issaid electromagnet means.
 7. The combination of claim 5 and wherein saidone of said pair of means is said switching circuit means.